Modified conjugated diene polymer and method for preparing the same

ABSTRACT

Disclosed are a modified conjugated diene polymer and a method for preparing the same. Provided are advantageously a modified conjugated diene polymer and a method for preparing the same which provide superior compatibility with an inorganic filler, heat generation, tensile strength and abrasion resistance, low fuel consumption and excellent resistance on wet roads.

This application is a continuation application of U.S. patentapplication Ser. No. 14/370,911, filed Jul. 7, 2014, which is a NationalStage Application of International Patent Application No.PCT/KR2013/006961 filed on Aug. 1, 2013, both of which are incorporatedherein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a modified conjugated diene polymer anda method for preparing the same. The present invention relates to amodified conjugated diene polymer which exhibits superior compatibilitywith an inorganic filler, heat generation, tensile strength and abrasionresistance, low fuel consumption and excellent resistance on wet roads,and a method for preparing the same.

BACKGROUND ART

Demands for stability, durability and low fuel consumption of vehiclesare increasing. Accordingly, there is an increasing demand for rubbersexhibiting excellent resistance on wet roads and mechanical strength andlow rolling resistance as materials for vehicle tires, in particular,tire treads contacting the roads.

Conventional tire treads have been produced using a conjugated dienerubber in conjunction with an inorganic filler in order to reinforce theproperties described above, but have problems of great hysteresis lossor low dispersibility.

DISCLOSURE Technical Problem

Therefore, the present invention has been made in view of the aboveproblems, and it is one object of the present invention to provide amodified conjugated diene polymer which exhibits superior compatibilitywith an inorganic filler, heat generation, tensile strength and abrasionresistance, low fuel consumption and excellent resistance on wet roads,and a method for preparing the same.

It is another object of the present invention to provide a rubbercomposition comprising the modified conjugated diene polymer and a tirecomprising the rubber composition.

It is yet another object of the present invention to provide a modifyingagent used for preparation of the modified conjugated diene polymer.

The above and other objects can be accomplished by the present inventiondescribed below.

Technical Solution

In accordance with one aspect of the present invention, provided is amodified conjugated diene polymer represented by the following Formula1:

wherein R₁ is an alkyl group or an alkylsilyl group, R₂ and R₃ are analkyl group, a is an integer of 1 to 3, l and k are an integer of 0 to2, m is an integer of 1 to 3, l+k+m satisfies 3, p is a conjugated dienepolymer chain and b is an integer of 1 to 3, wherein two R₁ bonded tonitrogen are identical or different when k is 2, and in the same way,corresponding groups are identical or different when l and m are 2 ormore.

In accordance with another aspect of the present invention, provided isa method for preparing a modified conjugated diene polymer comprising(a) polymerizing a conjugated diene monomer, or a conjugated dienemonomer and an aromatic vinyl monomer in the presence of a solvent usingan organometallic compound to prepare an active polymer having a metalend group, and (b) adding a compound represented by the followingFormula 2 to the active polymer to modify the active polymer:

wherein R₁ is an alkyl group or an alkylsilyl group, R₂ and R₃ are analkyl group, a is an integer of 1 to 3, and n is an integer of 0 to 2,wherein two R₁ bonded to nitrogen are identical or different when n is2, and in the same way, corresponding groups are identical or differentwhen 3-n is 2 or more.

In accordance with another aspect of the present invention, provided isa modified conjugated diene polymer rubber composition comprising 0.1 to200 parts by weight of an inorganic filler with respect to 100 parts byweight of the modified conjugated diene polymer.

In accordance with another aspect of the present invention, provided isa tire comprising the modified conjugated diene polymer rubbercomposition.

In accordance with yet another aspect of the present invention, providedis a modifying agent used for preparation of the modified conjugateddiene polymer.

Advantageous Effects

As apparent from the fore-going, the present invention advantageouslyprovides a modified conjugated diene polymer which exhibits superiorcompatibility with an inorganic filler, heat generation, tensilestrength and abrasion resistance, low fuel consumption and excellentresistance on wet roads, and a method for preparing the same.

BEST MODE

Hereinafter, the modified conjugated diene polymer, the method forpreparing the same, the rubber composition comprising the modifiedconjugated diene polymer and the tire comprising the rubber compositionwill be described in detail.

The modified conjugated diene polymer according to the present inventioncomprises a polymer represented by the following Formula 1:

wherein R₁ is an alkyl group or an alkylsilyl group, R₂ and R₃ are analkyl group, a is an integer of 1 to 3, l and k are an integer of 0 to2, m is an integer of 1 to 3, l+k+m satisfies 3, p is a conjugated dienepolymer chain, and b is an integer of 1 to 3, wherein two R₁ bonded tonitrogen are identical or different when k is 2, and in the same way,corresponding groups are identical or different when l and m are 2 ormore.

R₁ is for example an alkyl group or a C1-C12 alkyl group.

R₂ and R₃ are for example a C1-C12 alkyl group.

l is for example 0 or 1.

k is for example 0 or 1. Within this range, there are advantages in thathysteresis loss is reduced, and compatibility with an inorganic filler,in particular, silica is excellent.

m is for example 1 or 2 and, in another example, m is 2 or 3.

The total number of p is 1 to 9, 1 to 5, or 1 to 3. Within this range,there is an effect in that produced tires exhibit superior resistance onwet roads and low fuel consumption.

In Formula 1, for example, k is 1, l is 0, and m is 2.

In Formula 1, in another example, k is 1, l is 1, and m is 1.

The conjugated diene polymer chain is for example a chain comprising aconjugated diene monomer alone, or the conjugated diene monomer and anaromatic vinyl monomer.

In another example, the conjugated diene polymer chain may be a polymerchain comprising 0.0001 to 40% by weight, 10 to 35% by weight or 20 to30% by weight of the aromatic vinyl monomer, based on 100% by weight intotal of the conjugated diene monomer and the aromatic vinyl monomer.

The polymer chain comprising the conjugated diene monomer and thearomatic vinyl monomer may be for example a random polymer chain.

The conjugated diene monomer, for example, comprises at least oneselected from the group consisting of 1,3-butadiene,2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene,and 2-phenyl-1,3-butadiene.

The aromatic vinyl monomer, for example, comprises at least one selectedfrom the group consisting of styrene, α-methylstyrene, 3-methylstyrene,4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene,4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and1-vinyl-5-hexylnaphthalene. In another example, the aromatic vinylmonomer is styrene or α-methylstyrene.

The modified conjugated diene polymer, for example, has a Mooneyviscosity of 40 or higher, 40 to 90, 45 to 85, or 50 to 80.

The modified conjugated diene polymer, for example, has a number averagemolecular weight of 1,000 to 2,000,000 g/mol, 10,000 to 1,000,000 g/mol,or 100,000 to 500,000 g/mol.

The conjugated diene polymer, for example, has a vinyl content of 25% orhigher, 30 to 70%, or 40 to 60%. Within this range, there are advantagesin that glass transition temperature of polymer is increased,properties, such as running resistance and brake power, required forproduced tires are satisfied and fuel consumption is reduced.

The vinyl content means a content of a unit having a vinyl group, or acontent of a 1,2-added conjugated diene monomer rather than a 1,4-addedconjugated diene monomer with respect to 100% by weight of theconjugated diene monomer.

The modified conjugated diene polymer may, for example, have a PDI of0.5 to 10, 0.5 to 5, or 1.0 to 2.0.

Regarding viscoelasticity, the modified conjugated diene polymer, forexample, has a Tan δ at 0° C., measured at 10 Hz using DMA after mixingwith silica, of 0.6 to 1 or 0.9 to 1. Within this range, there is aneffect in that resistance on roads or wet roads is greatly improved, ascompared to the related art.

In addition, the modified conjugated diene polymer has, for example, aTan δ at 60° C., of 0.06 to 0.09, or 0.07 to 0.08. Within this range,rolling resistance or rotational resistance (RR) is advantageouslygreatly improved, as compared to the related art.

The method for preparing a modified conjugated diene polymer accordingto the present invention includes (a) polymerizing a conjugated dienemonomer, or a conjugated diene monomer and an aromatic vinyl monomer inthe presence of a solvent using an organometallic compound to prepare anactive polymer having a metal end group, and (b) adding a compoundrepresented by the following Formula 2 to the active polymer to modifythe active polymer:

wherein R₁ is an alkyl group or an alkylsilyl group, R₂ and R₃ are analkyl group, a is an integer of 1 to 3, and n is an integer of 0 to 2,wherein two R₁ bonded to nitrogen are identical or different when n is2, and in the same way, corresponding groups are identical or differentwhen 3-n is 2 or more.

R₁ to R₃ have been defined above.

The conjugated diene monomer, for example, comprises at least oneselected from the group consisting of 1,3-butadiene,2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, isoprene,and 2-phenyl-1,3-butadiene.

The aromatic vinyl monomer, for example, comprises at least one selectedfrom the group consisting of styrene, α-methylstyrene, 3-methylstyrene,4-methylstyrene, 4-propylstyrene, 1-vinylnaphthalene,4-cyclohexylstyrene, 4-(p-methylphenyl)styrene, and1-vinyl-5-hexylnaphthalene. In another example, the aromatic vinylmonomer is styrene or α-methylstyrene.

The aromatic vinyl monomer may be present in an amount of 0.0001 to 40%by weight, 10 to 35% by weight or 20 to 30% by weight, based on 100% byweight in total of the conjugated diene monomer and the aromatic vinylmonomer.

The solvent may for example comprise at least one selected from thegroup consisting of hydrocarbons, n-pentane, n-hexane, n-heptane,isooctane, cyclohexane, toluene, benzene and xylene.

The organometallic compound may for example comprise at least oneselected from the group consisting of organic alkali metal compounds,organolithium compounds, organosodium compounds, organopotassiumcompounds, organorubidium compounds and organocesium compounds.

In another example, the organometallic compound may comprise at leastone selected from the group consisting of methyl lithium, ethyl lithium,isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyllithium, n-decyl lithium, tert-octyl lithium, phenyl lithium, 1-naphthyllithium, n-eicosyl lithium, 4-butylphenyl lithium, 4-tolyl lithium,cyclohexyl lithium, 3,5-di-n-heptylcyclohexyl lithium and 4-cyclopentyllithium.

In another example, the organometallic compound is n-butyl lithium,sec-butyl lithium or a mixture thereof.

In another example, the organometallic compound may comprise at leastone selected from the group consisting of sodium naphthyl, potassiumnaphthyl, lithium alkoxide, sodium alkoxide, potassium alkoxide, lithiumsulfonate, sodium sulfonate, potassium sulfonate, lithium amide, sodiumamide and potassium amide. The organometallic compound may be used incombination with another organometallic compound.

The organometallic compound is for example used in an amount of 0.01 to10 mmol, 0.05 to 5 mmol, 0.1 to 2 mmol or 0.1 to 1 mmol, based on 100 gin total of the monomer.

A molar ratio of the organometallic compound to the compound representedby Formula 2 is for example 1:0.1 to 1:10, 1:0.5 to 1:10 or 1:0.5 to1:2.

The active polymer having a metal end group means a polymer wherein apolymer anion is bonded to a metal cation.

The method for preparing a modified conjugated diene polymer accordingto the present invention, for example, comprises further adding a polaradditive during (a) the polymerization.

The polar additive is for example a base. In another example, the polaradditive is ether, amine or a mixture thereof, or is selected from thegroup consisting of tetrahydrofuran, ditetrahydrofurylpropane,diethylether, cycloamylether, dipropyl ether, ethylene methyl etherdimethyl ether, ethylene dimethyl ether, diethylene glycol, dimethylether, tertiary butoxyethoxyethane bis(2-dimethylaminoethyl)ether,(dimethylaminoethyl)ethylether, trimethylamine, triethylamine,tripropylamine, and tetramethylethylenediamine. In another example, thepolar additive is ditetrahydrofurylpropane, triethylamine ortetramethylethylenediamine.

The polar additive may be for example used in an amount of 0.001 to 10g, 0.005 to 1 g, or 0.005 to 0.1 g, based on 100 g in total of the addedmonomer.

In another example, the polar additive may be used in an amount of 0.001to 10 g, 0.005 to 1 g, or 0.005 to 0.1 g, based on 1 mmol in total ofthe added organometallic compound.

When the conjugated diene monomer and the aromatic vinyl monomer arecopolymerized, a block copolymer may be readily prepared due todifference in reaction speed between the monomers. However, when thepolar additive is added, reaction speed of the vinyl aromatic compoundwhich has a low reaction speed is increased, and microstructure of thecopolymer corresponding thereto, for example, random copolymer isadvantageously induced.

The polymerization (a) may be for example anionic polymerization.

In another example, the polymerization (a) may be living anionicpolymerization for obtaining active ends by growth reaction by anions.

The polymerization (a) may be for example polymerization at an elevatedtemperature or polymerization at a fixed temperature.

The polymerization at an elevated temperature means a polymerizationmethod which includes elevating a reaction temperature by heating afteradding an organometallic compound. The polymerization at a fixedtemperature means a polymerization method which does not include heatingafter adding an organometallic compound.

A temperature of the polymerization (a) is for example −20 to 200° C., 0to 150° C. or 10 to 120° C.

In the modification (b), for example, one or more types, or two or threetypes of the compound represented by Formula 1 may be added.

In addition, the modification (b) may include reaction, for example, at0 to 90° C. for one minute to 5 hours.

The method for preparing a modified conjugated diene polymer accordingto the present invention may be, for example, batch or continuouspolymerization including one, two or more reactors.

The modified conjugated diene polymer may be, for example, preparedaccording to the method for preparing a modified conjugated dienepolymer.

The modified conjugated diene polymer rubber composition according tothe present invention comprises 100 parts by weight of the modifiedconjugated diene polymer and 0.1 to 200 parts by weight of an inorganicfiller.

The modified conjugated diene polymer rubber composition may furtherinclude, for example, another conjugated diene polymer.

The another conjugated diene polymer may be, for example,styrene-butadiene rubber (SBR), butadiene rubber (BR) or a mixturethereof.

The SBR may be, for example, a solution styrene-butadiene rubber (SSBR).

The modified conjugated diene polymer rubber composition according tothe present invention may, for example, include 20 to 100 parts byweight of the modified conjugated diene polymer and 0 to 80 parts byweight of the another conjugated diene polymer.

In another example, the modified conjugated diene polymer rubbercomposition may include 20 to 99 parts by weight of the modifiedconjugated diene polymer and 1 to 80 parts by weight of the anotherconjugated diene polymer.

In another example, the modified conjugated diene polymer rubbercomposition may comprise 10 to 100 parts by weight of the modifiedconjugated diene polymer, 0 to 90 parts by weight of the anotherconjugated diene polymer (with the proviso that the total weight of thepolymers is 100 parts by weight), 0 to 100 parts by weight of carbonblack, 5 to 200 parts by weight of silica and 2 to 20 parts by weight ofa silane coupling agent.

In another example, the modified conjugated diene polymer rubbercomposition may comprise 10 to 100 parts by weight of the modifiedconjugated diene polymer, 0 to 90 parts by weight of the anotherconjugated diene polymer, 0 to 100 parts by weight of carbon black, 5 to200 parts by weight of silica and 2 to 20 parts by weight of a silanecoupling agent, wherein the total weight of the modified conjugateddiene polymer and the another conjugated diene polymer is 100 parts byweight.

In another example, the modified conjugated diene polymer rubbercomposition according to the present invention is prepared by mixing 10to 99 parts by weight of the modified conjugated diene polymer and 1 to90 parts by weight of the another conjugated diene polymer with 1 to 100parts by weight of carbon black, 5 to 200 parts by weight of silica and2 to 20 parts by weight of a silane coupling agent.

The inorganic filler may be present in an amount of, for example, 10 to150 parts by weight, or 50 to 100 parts by weight.

The inorganic filler may be, for example, carbon black, a silica filleror a mixture thereof.

In another example, the inorganic filler may be silica. In this case,advantageously, dispersibility is greatly improved and hysteresis lossis greatly decreased because an end of the modified conjugated dienepolymer is bonded to (or capped with) silica particles.

The modified conjugated diene polymer rubber composition may for examplefurther comprise 1 to 100 parts by weight of an oil.

The oil may be, for example, a mineral oil, a softening agent or thelike.

The oil may be, for example, used in an amount of 10 to 100 parts byweight or 20 to 80 parts by weight, with respect to 100 parts by weightof the conjugated diene copolymer. Within this range, there are effectsin that properties are efficiently exhibited, the rubber composition issuitably softened and processability is thus excellent.

The modified conjugated diene polymer rubber composition may be forexample used as a material for tires or tire treads.

The tire may be produced from the modified conjugated diene polymerrubber composition.

The modifying agent according to the present invention is represented bythe following Formula 2:

wherein R₁ is an alkyl group or an alkylsilyl group, R₂ and R₃ are analkyl group, a is an integer of 1 to 3, and n is an integer of 0 to 2,wherein two R₁ bonded to nitrogen are identical or different when n is2, and similarly, corresponding groups are identical or different when3-n is 2 or more.

Hereinafter, preferred examples will be provided for betterunderstanding of the present invention. It will be apparent to thoseskilled in the art that these examples are only provided to illustratethe present invention and various modifications and alterations arepossible within the scope and technical range of the present invention.Such modifications and alterations fall within the scope of claimsincluded herein.

EXAMPLE Example 1

270 g of styrene, 710 g of 1,3-butadiene, 5,000 g of n-hexane, and 0.9 gof 2,2-bis(2-oxolanyl)propane as a polar additive were added to a 20 Lautoclave reactor and an inner temperature of the reactor was elevatedto 40° C. When the inner temperature of the reactor reached 40° C., 4mmol of n-butyl lithium was added to the reactor and an adiabatictemperature-rising reaction was performed until the reaction wasstabilized. About 20 minutes after the adiabatic temperature-risingreaction was finished, 20 g of 1,3-butadiene was added to the reactor.After 5 minutes, 4.4 mmol of tris(trimethoxysilyl) amine was added as amodifying agent to the reactor and reaction was performed for 15minutes. Then, reaction was stopped using methanol and 5 ml of a 0.3 wt% solution of butylated hydroxytoluene (BHT) as an antioxidant in hexanewas then added to the reaction mixture.

The polymerization product was added to warm water heated by steam, themixture was stirred, the solvent was removed, and the resulting solutionwas then roll-dried to remove the residual solvent and water, therebypreparing a modified conjugated diene polymer. Analysis results of themodified conjugated diene polymer thus prepared are shown in thefollowing Table 1.

Example 2

A modified conjugated diene polymer was prepared in the same manner asin Example 1, except that 1.3 mmol of tris(trimethoxysilyl) amine wasadded. Analysis results of the modified conjugated diene polymer areshown in the following Table 1.

Example 3

A modified conjugated diene polymer was prepared in the same manner asin Example 1, except that that 0.4 mmol of tris(trimethoxysilyl) aminewas added.

Example 4

A modified conjugated diene polymer was prepared in the same manner asin Example 1, except that that 4.8 mmol of tris(triethoxysilyl) aminewas added as a modifying agent.

Comparative Example 1

270 g of styrene, 710 g of 1,3-butadiene, 5,000 g of n-hexane, and 0.9 gof 2,2-bis(2-oxolanyl)propane as a polar additive were added to a 20 Lautoclave reactor and an inner temperature of the reactor was elevatedto 40° C. When the inner temperature of the reactor reached 40° C., 4mmol of a lithium initiator was added to the reactor and an adiabatictemperature-rising reaction was performed until the reaction wasstabilized. About 20 minutes after the adiabatic temperature-risingreaction was finished, 20 g of 1,3-butadiene was added to the reactor.After 5 minutes, reaction was performed for 15 minutes using 2.4 mmol ofdimethyldichlorosilane as a coupling agent. Then, reaction was stoppedusing methanol and 5 ml of a 0.3 wt % solution of butylatedhydroxytoluene (BHT) as an antioxidant in hexane was then added to thereaction mixture.

The polymerization product was added to warm water heated by steam, themixture was stirred, the solvent was removed, and the resulting solutionwas then roll-dried to remove the residual solvent and water, therebypreparing an un-modified conjugated diene polymer. Analysis results ofthe un-modified conjugated diene polymer thus prepared are shown in thefollowing Table 1.

Comparative Example 2

Analysis results of an unmodified conjugated diene polymer (5025-2HM,produced by Lanxess Deutschland Gmbh) which is the most commerciallyavailable are shown in the following Table 1.

Test Example

Analysis of conjugated diene polymers prepared in Examples 1 to 4 andComparative Examples 1 to 2 was performed in accordance with thefollowing method.

a) Mooney viscosity: measured at 100° C. for 4 minutes using MV-2000produced by ALPHA Technologies and two specimens having a weight of 15 gor more after pre-heating for one minute.

b) Number average molecular weight (Mn), weight average molecular weight(Mw), and polydispersity (PDI): measured using analysis results of GPCat 40° C. The column herein used was a combination of two PLgel Olexiscolumns produced by Polymer Laboratories and one PLgel mixed-C column.All newly replaced columns were mixed bed-type columns. In addition,polystyrene (PS) was used as a GPC standard material for determinationof molecular weight.

TABLE 1 Comparative Examples Examples Items 1 2 3 4 1 2 Sample A B C D EF n-butyllithium (mmol) 4 4 4 4 4 4 Polar additive (g) 0.9 0.9 0.9 0.90.9 0.9 Modifying agent a 4.8 1.3 0.4 — — — (mmol) b 4.8 Coupling agentc — — — — 2.4 — TDAE oil phr — — — — — 37.5 Mooney viscosity 63 80 51 6058 61 (MV) NMR (%) SM 26 26 26 26 26 26 Vinyl 44 44 43 44 44 50 GPC(×10⁴) Mn 37 42 28 35 31 39 Mw 49 63 34 46 37 69 PDI 1.3 1.5 1.2 1.3 1.21.8 a: tris(trimethoxysilyl) amine b: tris (triethoxysilyl) amine c:dimethyldichlorosilane

TABLE 2 (Unit: parts by weight) S-1 S-2 Rubber 100.0 137.5 Silica 70.070.0 Coupling 11.02 11.2 agent Oil 33.75 — Zinc oxide 3.0 3.0 Stearicacid 2.0 2.0 Antioxidant 2.0 2.0 Anti-aging 2.0 2.0 agent Wax 1.0 —Rubber 1.75 1.75 accelerator Sulfur 1.5 1.5 Vulcanization 2.0 2.0accelerator Total weight 230.2 234.0

Examples 5 to 8 and Comparative Examples 3 and 4

Samples A to F shown in Table 1 as rubber raw materials were mixed undermixing conditions shown in the following Table 2 to prepare conjugateddiene polymer rubber compositions. A to E were mixed under mixingconditions of S-1 (Examples 5 to 8 and Comparative Example 3) and F wasmixed under mixing conditions of S-2 (Comparative Example 4).

The rubber compositions of the conjugated diene polymer were kneadedusing a Banbury mixer equipped with a temperature controller as follows.In primary kneading, a rubber raw material (conjugated diene polymer), afiller, an organosilane coupling agent, an oil, zinc oxide, a stearicacid antioxidant, an anti-aging agent, a wax and accelerators wereprimarily kneaded at 80 rpm. At this time, the temperature of thekneader was controlled and a primary mixture was obtained at a dischargetemperature of 140 to 150° C. In secondary kneading, after the primarymixture was cooled to room temperature, a rubber, sulfur and avulcanization accelerator were added to the kneader and a secondarymixture was obtained at a discharge temperature of 45 to 60° C. Intertiary kneading, the secondary mixture was molded and was vulcanizedusing a vulcanization press at 180° C. for T90+10 minutes to prepare avulcanized rubber.

Physical properties of the prepared vulcanized rubbers are shown in thefollowing Table 3.

Physical properties of the prepared vulcanized rubbers were measured inaccordance with the following method.

1) Tensile Strength Test

Tensile strength at break and tensile strength at an elongation of 300%(300% modulus) of specimens were measured by tensile strength testing inaccordance with ASTM 412.

2) Viscoelasticity

A dynamic mechanical analyzer produced by TA Instrument was used. Tan δwas measured while changing strain in a torsional mode at a frequency of10 Hz and at different measurement temperatures of 0 to 60° C. Payneeffect was represented as a difference between a minimum and a maximumat a strain of 0.2% to 40%. As Payne effect decreases, dispersibility ofa filler such as silica is improved. As Tan δ at a low temperature of 0°C. increases, resistance on wet roads is improved, and as Tan δ at ahigh temperature of 60° C. decreases, hysteresis loss is low, androlling resistance of tires is low, that is, fuel consumption thereof isreduced.

TABLE 3 Comparative Examples Examples Items 5 6 7 8 3 4 Samples A B C DE F 300% modulus 120 119 110 117 104 98 (Kgf/cm²) Tensile 183 190 165175 168 161 strength (Kgf/cm²) Tan δ at 0° C. 0.729 0.720 0.705 0.7260.542 0.547 Tan δ at 60° C. 0.086 0.086 0.088 0.085 0.098 0.085 ^(Δ)G′at 60° C. 0.42 0.41 0.48 0.45 0.74 0.56 (Payne effect)

As can be seen from Table 3 above, the modified conjugated diene polymerrubber compositions according to Examples 5 to 8 exhibited a greatincrease in 300% modulus (tensile stress) and tensile strength, and ahigh Tan δ at 0° C., as compared to Comparative Examples 3 and 4, whichindicates that tires comprising the modified conjugated diene polymerrubber compositions exhibited great improvement of resistance on wetroads.

In addition, the modified conjugated diene polymer rubber compositionsof Examples 5 to 8 exhibited a low Tan δ at 60° C., as compared toComparative Examples 3 and 4. Tires comprising the modified conjugateddiene polymer rubber compositions exhibited superior resistance on wetroads and low rolling resistance (low fuel consumption) as compared tothe related art.

For reference, Comparative Example 4 exhibited a low Tan δ at 60° C. Thereason for the low Tan δ is that Tg of polymer was changed due todifference in vinyl content. That is, the low Tan δ at 60° C. wasconsidered to be due to curve shift by Tg, rather than variation inphysical properties.

What is claimed is:
 1. A modified conjugated diene polymer representedby the following Formula 1:

wherein R₁ is an alkyl group or an alkylsilyl group, R₂ and R₃ are analkyl group, a is an integer of 1 to 3, 1 is an integer of 1 or 2, and kis an integer of 0 to 2, m is an integer of 1 to 3, l+k+m satisfies 3, Pis a conjugated diene polymer chain, and b is an integer of 1 to 3,wherein two R₁ bonded to nitrogen are identical or different when k is2, and corresponding groups are identical or different when l and m are2 or more.
 2. The modified conjugated diene polymer according to claim1, wherein k is 0 or
 1. 3. The modified conjugated diene polymeraccording to claim 1, wherein k is 1, l is 1 and m is
 1. 4. The modifiedconjugated diene polymer according to claim 1, wherein the conjugateddiene polymer chain further comprises an aromatic vinyl monomer.
 5. Themodified conjugated diene polymer according to claim 4, wherein themodified conjugated diene polymer comprises 10 to 40% by weight of thearomatic vinyl monomer, based on 100% by weight in total of theconjugated diene monomer and the aromatic vinyl monomer.
 6. The modifiedconjugated diene polymer according to claim 1, wherein the modifiedconjugated diene polymer has a number average molecular weight of 1,000to 2,000,000 g/mol.
 7. The modified conjugated diene polymer accordingto claim 1, wherein the modified conjugated diene polymer has a vinylcontent of 25% or more.
 8. The modified conjugated diene polymeraccording to claim 1, wherein the modified conjugated diene polymer hasa Mooney viscosity of 40 or more.
 9. A modified conjugated diene polymerrubber composition comprising 0.1 to 200 parts by weight of an inorganicfiller with respect to 100 parts by weight of the modified conjugateddiene polymer according to claim
 1. 10. The modified conjugated dienepolymer rubber composition according to claim 9, wherein the compositioncomprises 10 to 100 parts by weight of the modified conjugated dienepolymer, 0 to 90 parts by weight of another conjugated diene polymer, 0to 100 parts by weight of carbon black, 5 to 200 parts by weight ofsilica and 2 to 20 parts by weight of a silane coupling agent.
 11. Themodified conjugated diene polymer rubber composition according to claim9, wherein the inorganic filler is a silica filler.
 12. A tirecomprising the modified conjugated diene polymer rubber compositionaccording to claim 9.